Atypical Protein Kinase C Is Involved in the Evolutionarily Conserved PAR Protein Complex and Plays a Critical Role in Establishing Epithelia-Specific Junctional Structures

• Published in: The Journal of cell biology 2001-03, Vol.152 (6), p.1183-1196
• Main Authors: Suzuki, Atsushi, Yamanaka, Tomoyuki, Hirose, Tomonori, Manabe, Naoyuki, Mizuno, Keiko, Shimizu, Miki, Akimoto, Kazunori, Izumi, Yasushi, Ohnishi, Tetsuo, Ohno, Shigeo
• Format: Article
• Language: English
• Subjects: Actins - metabolism; Adenoviridae - genetics; Adenoviridae - metabolism; Adenoviruses; Adipocytes; Amino acids; Animals; Antibodies; Blotting, Western; Cadherins - metabolism; Caenorhabditis elegans Proteins; Calcium; Calcium - metabolism; Carrier Proteins; Cell Adhesion Molecules; Cell Line; Cell Polarity; Cells; Embryos; Epithelial cells; Epithelial Cells - cytology; Epithelial Cells - physiology; Epithelial Cells - ultrastructure; Fluorescent Dyes - metabolism; Gene Transfer Techniques; Helminth Proteins - metabolism; Macromolecular Substances; Membrane Lipids - metabolism; Membrane Proteins - metabolism; Microscopy, Fluorescence; Occludin; Original; Phosphoproteins - metabolism; Precipitin Tests; Protein Kinase C - genetics; Protein Kinase C - metabolism; Protein-Serine-Threonine Kinases; Proteins - genetics; Proteins - metabolism; Sertoli cells; Sodium-Potassium-Exchanging ATPase - metabolism; Tight junctions; Tight Junctions - metabolism; Zonula Occludens-1 Protein
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.152.6.1183

We have previously shown that during early Caenorhabditis elegans embryogenesis PKC-3, a C. elegans atypical PKC (aPKC), plays critical roles in the establishment of cell polarity required for subsequent asymmetric cleavage by interacting with PAR-3. Together with the fact that aPKC and a mammalian PAR-3 homologue, aPKC-specific interacting protein (ASIP), colocalize at the tight junctions of polarized epithelial cells, this suggests a ubiquitous role for aPKC in establishing cell polarity in multicellular organisms. Here, we show that the over-expression of a dominant-negative mutant of aPKC (aPKCkn) in MDCK II cells causes mislocalization of ASIP/PAR-3. Immunocytochemical analyses, as well as measurements of paracellular diffusion of ions or non-ionic solutes, demonstrate that the biogenesis of the tight junction structure itself is severely affected in aPKCkn-expressing cells. Furthermore, these cells show increased interdomain diffusion of fluorescent lipid and disruption of the polarized distribution of Na+, K+-ATPase, suggesting that epithelial cell surface polarity is severely impaired in these cells. On the other hand, we also found that aPKC associates not only with ASIP/PAR-3, but also with a mammalian homologue of C. elegans PAR-6 (mPAR-6), and thereby mediates the formation of an aPKC-ASIP/PAR-3-PAR-6 ternary complex that localizes to the apical junctional region of MDCK cells. These results indicate that aPKC is involved in the evolutionarily conserved PAR protein complex, and plays critical roles in the development of the junctional structures and apico-basal polarization of mammalian epithelial cells.